William Edward Binney is a former highly placed intelligence official with the United States National Security Agency (NSA) turned whistleblower who resigned in 2001. Binney spent more than 30 years working at the NSA, and has been described as one of the best analysts in its history. He was a high-profile critic of his former employers during the George W. Bush administration.

He continues to speak out about the NSA's data collection policies, and continues interviews in the media regarding his experiences and his views on communication intercepts by governmental agencies of American citizens. In a legal case, Binney has testified in an affidavit that the NSA is in deliberate violation of the US Constitution.

In September 2002, he, along with J. Kirk Wiebe and Edward Loomis, asked the US Defense Department to investigate the NSA for allegedly wasting "millions and millions of dollars" on Trailblazer, a system intended to analyse data carried on communications networks such as the Internet. Binney had been one of the inventors of an alternative system, ThinThread, which was shelved when Trailblazer was chosen instead. Binney has also been publicly critical of the NSA for spying on US citizens, saying of its expanded surveillance after the September 11, 2001 attacks that "it's better than anything that the KGB, the Stasi, or the Gestapo and SS ever had, as well as noting Trailblazer's ineffectiveness and unjustified high cost compared to the far less intrusive ThinThread. He was furious that the NSA had not uncovered the 9/11 plot and stated that intercepts it had collected but not analysed likely would have garnered timely attention with his leaner more focused system.

Binney was born in Pennsylvania in the US, and graduated from Pennsylvania State University. A cryptanalyst-mathematician, he is known for his work in cryptography and SIGINT analysis. He received the Joe A. Callaway Award for Civic Courage for Meritorious Civilian Service in 2012.